1. Field of the Invention
The present invention relates generally to orthopedic appliances. More particularly, the invention concerns a novel method for making finished functional orthotics by using various critical measurements made of the patient's feet.
2. Discussion of the Prior Art
Orthopedic appliances, or foot supports, having various shapes and configurations have been known for many years. The prior art appliances range from simple foam, leather, cork, or sponge rubber arch supports that can be purchased in drugstores to sophisticated, custom-fitted orthotics formed of various rigid or semirigid materials. These latter devices, while much more effective than the former, are typically quite expensive and are generally constructed by orthopedic laboratories in accordance with detailed prescriptions provided by the examining doctor.
Generally speaking, the primary function of an orthotic is to correctly limit the complex motions of excessive pronation and supination. Pronation may be simply described as the flattening or rolling inward of the foot as the foot strikes the ground as during walking or running. Excessive pronation can cause the tibia and fibula to rotate inwardly sometimes placing severe strain on the leg muscles. Supination, on the other hand, is the rolling outward of the foot during walking or running. When either of these motions become excessive, painful damage to the knees, ankles and feet can occur.
In making the more sophisticated functional orthotics, the conventional practice, which has remained essentially unchanged for many years, is to first make an impression of the patient's foot. This impression, which may be made in plaster of paris or in a crushable, foam-like material, is forwarded to the orthopedic laboratory along with the examining doctor's instructions. One method of making the impression, or negative depression, using foam blocks is described in U.S. Pat. No. 3,320,347 issued to Greenawalt. This method, as described by Greenawalt, comprises placing a foam block on the floor, centering one of the patient's feet relative to the block and then having the patient stand so that his weight is equally divided on both feet. As the patient's weight is placed on the foam block, the foam cells of the block will be crushed and a negative impression of the patient's foot will be created.
The thrust of the Greenawalt method is to use the impression made in the crushable foam block to make various measurements, visual observations and touch evaluations which serve as the basis for constructing the corrective arch support. For example, measurements are made of the length and width of the impression and observations of the position of the metatarsal heads, of plantar abnormalities in the inner and outer longitudinal arch and of the presence and degree of supination are made. These measurements and observations are then used in laying out the dimensions and sizes of the leather blanks which are to be used for constructing the corrective arch support.
Another prior art approach followed by many orthopedic laboratories in constructing functional orthotics involves pouring a solution of plaster of paris into the impression, or negative depression, to make an uncorrected replica or cast of the patient's foot. This having been done, the uncorrected replica which provides an exact duplication of the contours of the lower surface of the patient's foot, is corrected in the manner prescribed by the examining doctor. For example, the uncorrected replica is often wedged or adjusted to simulate the position of the foot in the neutral position or in the position which the doctor wishes to control foot function. The neutral position of the foot is the position wherein the foot is neither supinated nor pronated and the midtarsal joint is maximally pronated. In this neutral position, the foot typically transfers force most effectively. In biomechanical terms the foot must ideally absorb the force of gravity at heel contact and then create a rigid lever to correctly propel the body forward for the next step. When the foot is not in or near the neutral position, it cannot absorb force nor can it create an effective lever for propelling the body forward in a proper manner. Such a problem can cause the foot structure to break down and, over time, lead to severe neck pain, back pain, foot pain, bunions, heel spurs, and the like.
The wedging step involves first bisecting the posterior aspect of the calcaneus and then wedging the cast until this bisection is generally perpendicular to the horizontal plane. The wedging, per se, is generally accomplished by adding a plaster forefoot platform to the cast. Preferably, the platform extends from about one centimeter proximal to the first metatarsal head and the fifth metatarsal head to the sulcus area and spans the positive mold from the medial aspect (outside edge of first toe) to the lateral aspect (outside edge of fifth toe).
Typically, the wedged mold is then further modified with a plaster of paris buildup to account for fat pad expansion around the heel and along the lateral foot border, to allow for compression of the medial arch and transverse arch, and to create a smooth transition from the forefoot platform to the arch and midfoot.
It is apparent from the foregoing that the method for correcting the uncorrected replica is a complex, time-consuming, and highly labor intensive operation. Further, the prior art method is somewhat imprecise and is highly dependent on the skill of the particular technician involved.
Although the same basic principles are used by the laboratory technician to correct the uncorrected replica formed from the impression of the patient's foot, experience has shown that no two people will correct a particular replica in exactly the same way. Thus, if two identical uncorrected replicas were to be sent to two different orthopedic laboratories, the orthotic returned to the doctor would be different in various respects. This is because the laboratory technician who makes the corrections is of necessity required to make various subjective decisions based upon his own experience and capabilities. For example, no two feet are the same length and width, even on the same patient. Nevertheless the examining doctor, or other licensed professional, typically wants the two orthotics made for the same patient to look symmetrical. Accordingly, the technician is forced to subjectively judge where the forefoot platforms should be located and how much expansion should be placed on each foot. No two technicians or laboratories will make the same decisions in the same way.
Further contributing to the impreciseness of the prior art techniques for making functional orthotics is the method of forming the orthotic from the corrected replica. Basically, this method involved thermal forming of a layer of polyolefin plastic sheet over the lower surface of the corrected replica. If the forming step is correctly done and the polyolefin sheet is properly heated and cooled, the upper surface of the sheet will correspond substantially to the lower surface of the corrected replica. One such method of thermal forming is described in U.S. Patent No. 4,702,255 issued to Schenkel. However, if the forming step is incorrectly done, precise replication of the lower surface of the corrected replica will not result.
For the foregoing reasons, the products made by different laboratories are somewhat different and even the corrections made within a single laboratory may be different from foot to foot. Further contributing to deficiencies in prior art orthotics is the absence of reliable methods for analyzing the patient's foot impressions and the inability of a given orthotic constructed from the impression to, in fact, properly control the patient's foot.
From an exhaustive study made by the present inventor of literally thousands of orthotics made in accordance with the prior art processes discussed in the preceding paragraphs, a most surprising discovery was made. Since the conventional wisdom has been that the foot of each patient is unique with no two feet being alike, those working in the field have presumed that no two orthotics made by the previously discussed prior art process would be alike. Surprisingly, the studies made by the present inventor indicate that this, in fact, is not the case. These studies included the careful measurement of the contour of each of a large number of uncorrected replicas presented for correction followed by the careful measurement of the corrected contour of each corrected replica produced in the laboratory in accordance with the processes described in the preceding paragraphs. An analyses of the measurements showed that, while the uncorrected replicas typically varied in certain respects, many of the corrected replicas and the orthotics formed therefrom were nearly functionally identical and fell into rather well defined groups.
Based on the discovery that families of different, but related uncorrected replicas, when corrected by traditional processes, produced nearly identical corrected replicas, the present inventor reasoned that a permanent corrected replica in the nature of a male-forming master, could be constructed and used repeatedly to form final orthotics for each of these identical families. In this way, the substantial amount of labor required to correct each replica of the group of uncorrected replicas which made up the family could be avoided. Continuing studies by the inventor of additional uncorrected replicas received by the laboratory enabled the identification of a large number of identifiable groups of uncorrected replicas which, when corrected, would produce a substantially functionally identical finished orthotic. This information then made it possible to construct a number of forming masters for each of the identified families. After a large inventory of forming masters were then constructed, the next step in the development was to analyze each new uncorrected replica received by the laboratory and identify it with one of the previously identified families of uncorrected replicas which, when corrected, would produce a virtually identical finished orthotic. The forming master associated with the identified family was then used to form the finished orthotic for the newly received uncorrected replica rather than laboriously constructing a corrected replica and using it to form the finished orthotic for the patient.
The approach to making finished orthotics described in the preceding paragraphs was successfully commercialized and the orthotics made by the process were marketed by KLM Laboratories, Inc., of Valencia, Calif., under the name and style "SYSTEM RX". While this novel process was less labor intensive than the traditional prior art process whereby each uncorrected replica was corrected and then used to form the finished orthotic, the many processing difficulties and substantial labor involved in high temperature forming of the orthotic from a selected one of the male-forming molds remained. In a manner presently to be described, the methods of the present invention elegantly avoids the difficult, costly and time consuming step of high temperature forming and finishing of the orthotics from the male-forming masters and produces even a higher quality finished product at a significantly lower cost.
Before discussing the details of the present invention, it should be pointed out that others working in the field have also devised means for reducing the labor costs involved in the hand correction of each of the uncorrected replicas received by the processing laboratory. One such approach is disclosed in U.S. Pat. No. 5,054,148 issued to Grumbine. The Grumbine process involves the use of a computer-controlled mill to produce each individual orthotic from a monolithic workpiece. In accordance with the process, the specific contour of the top and bottom surface of an orthotic for a particular patient is first described and stored in terms of x, y, z coordinates and subsequently formatted such that a particular x, y, z coordinate, i.e. a specific longitudinal and lateral position on a workpiece yields a particular height (z) positioning of the machine tool. The machine tool is then guided along parallel paths through the workpiece while the machine tool's height is automatically adjusted to conform with the desired surface contour.
Although the Grumbine process and other somewhat similar prior art, computer-controlled milling operations developed by others working in the field have proven generally satisfactory, a considerable investment in sophisticated tooling such as scanners, computers and large computer-controlled milling machines is required. In addition, each order requires a unique set up and milling process which increases the overall cost per order.
Another prior art approach to making custom-made shoe inserts is described in U. S. Patent No. 4,876,758 issued to Rolloff et al. This patent discloses a foot impression unit which is provided with an array of gauging elements, a control mechanism for urging the gauging elements into contact with the undersurface of a person's foot to form an impression of the undersurface of the foot and a sensing mechanism for scanning the gauging elements to produce digital signals indicative of the positions of the gauging elements. These digital signals are stored and processed by a computer to provide a stored data record serving as a digital representation of the impression of the undersurface of the foot. The computer may also be employed to provide stored additional information for modifying that data record to compensate for a perceived defect of the foot with the x, y, z information derived. Once again, the custom-made shoe insert is made by a conventional computer controlled milling machine using the stored data for a particular patient. Once again, each order requires expensive and time consuming set-up and milling operations.
As will be better understood from the discussion which follows, the methods of the present invention uniquely overcome most of the drawbacks of the prior art processes for producing orthotics by providing a fast, accurate, efficient, and non-labor intensive process for making high quality precision orthotics in very high volumes.